Climate Facts in Numbers:

1.5: The average global temperature increase in degrees celsuis in the Paris Agreement “to limit the temperature increase to 1.5oC”, a threshold we have already almost reached.

97%: The percentage of scientists who agree that warming trends over the past century are very likely caused by human activity.

115,000 Years: When the world was last this warm.

4 Million Years: Time since the planet has experienced such high levels of carbon dioxide (CO2) in the atmosphere.

1950: Year when atmospheric CO2 levels broke records from the previous 400,000 years, sharply rising and continuing to grow.

16: Number of record-breaking hottest years since 2000, with 2016 being the hottest year yet.

30%: The increase in acidity of the world’s oceans.

50%: The amount of the coral reef in the Great Barrier Reef affected by coral bleaching.

8 inches (203mm): Rise in global sea levels over the last century. The rate of rise has nearly doubled in the last two decades.

50%: Up to half of all species could be lost by the end of this century.

14%: The increase Irish winters are expected to become wetter by mid-century.

20%: The frequency of heavy precipitation events during Irish winters.

5%: Amount of average increase in Irish annual rainfall.

192%: The expected increase of people living in Irish coastal flood-prone areas.

400 Million: The Irish emit the same amount of greenhouse gases as the poorest 400 million people on the planet.

0.1%: Climate change would cost less than 0.1% of GDP a year to address.

CO2 levels over past 400,000 years

Arctic Sea-ice Decline

Sea-Level Anomaly since 1850

Climate Change Science

Causes:

Light waves travel from the sun to Earth’s atmosphere. Light has a short wavelength and slices through the atmosphere unimpeded. Some reflects from the surface of the earth (by clouds, ice and other reflective surfaces) and is re-radiated back into space. The rest is absorbed by the natural greenhouse gas layer.

This natural layer of greenhouse gases is being thickened by human activities, mainly the burning of fossil fuels. Carbon dioxide (CO2) concentrations have increased by 40 percent since pre-industrial times, mainly from fossil fuel burning, and secondly from changes in how we use our land, agriculture and deforestation. [1]

As the greenhouse gas layer gets thicker. Some of the outgoing infrared radiation is trapped by the earth’s atmosphere and warms it, which in turn traps more of the infrared radiation and the temperature goes up. [2]

The atmosphere is not a vast, limitless space as we might imagine it. It is a thin band and is equivalent to the skin of an apple, if comparing earth to a whole apple. We are putting 110 million tons of global warming pollution into that small space every hour!

The planet has not experienced such high levels of carbon dioxide (CO2) in the atmosphere for 4 million years [3]

The world was last this warm about 115,000 years ago when sea level was 6-9 meters (20-30ft) higher than today [4]

Effects:

The extra heat (energy) in the atmosphere has multiple effects. The intensification of the water cycle means more water is evaporated from our oceans. Also, as the air gets warmer, it can hold more water vapour (also a green house gas). Heavy downpours get heavier, causing more flooding [5]

Snowpacks melt earlier in the year, leading to more spring flooding, but less water in the heat of summer.

There are longer intervals in drought-stricken areas between downpours, making droughts even worse. More water also evaporates more quickly from the soil, making droughts deeper and longer still.

The same extra heat that evaporates more water from the ocean, causing bigger downpours and floods also pulls moisture even more quickly from the soil, causing longer and deeper droughts [5]

Up to 50% of all species could be lost this century [6]

On a global basis 90% of the extra heat goes into the oceans [7]. This is a factor in sea level rise, as the heated oceans expand.

The extra carbon that is being absorbed by the oceans, has changed the acidity of the water by 25 – 30%, causing major problems for sea crustaceans i.e. crabs, oysters etc. to form their shells and especially problematic for coral reefs. This change in acidity is causing “coral bleaching”, which kills the coral reefs, where for example 93% of all coral in the Great Barrier Reef was effected [8]

Sea-level rise is also being caused by the melting land based glaciers. The two main glacial ice-sheets are Greenland and Antarctica. On Greenland summer melt on the ice sheet increased by 30% [9]

Projections suggest an increase in global sea levels in the range of 0.26 to 0.55m for the low emissions scenario and 0.52-0.98 for the high emissions scenario. However due to an as yet limited understanding of some of the important effects that contribute to rates of increase, a best estimate for sea level rise cannot be provided with confidence, and estimates of up to 4-6 m have been projected by some models [10]

Global sea level rose about 200mm (8 inches) in the last century. The rate in the last two decades, however, is nearly double that of the last century [11]

Climate Change News

2016 was the hottest year on record, setting a new high for the third year in a row, with scientists firmly putting the blame on human activities that drive climate change and showed 16 of the 17 hottest years on record have been this century [12]

The record-smashing temperatures in 2016 led to searing heatwaves across the year: a new high of 42.7C (108.9F) was recorded in Pretoria, South Africa in January; Mae Hong Son in Thailand saw 44.6C (112.3F) on 28 April; Phalodi in India reached 51.0C (123.8F) in May, and Mitribah in Kuwait recorded 54.0C (129.2F) in July.

Warmer oceans saw coral mortality of up to 50% in parts of Australia’s Great Barrier Reef and bleaching of 75% of Japan’s biggest reef [13]

Sea ice extent in Arctic and Antarctic reached record lows last November. The ‘almost unprecedented’ event attributed to warm temperatures and winds, with some areas more than 20C (36F) warmer than usual [14]>

Soaring Arctic temperatures ‘strongly linked’ to recent extreme weather events, say scientists at cutting edge of climate change research and ‘already affecting weather patterns where you live right now’ [15]

The world was last this warm about 115,000 years ago and the planet has not experienced such high levels of carbon dioxide (CO2) in the atmosphere for 4 million years [16]

Avoiding dangerous levels of climate change is still just about possible, but will require unprecedented effort and coordination from governments, businesses, citizens and scientists in the next three years, a group of prominent experts has warned [17]

The world will look a very different place if it warms by 4oC by the end of the century. See link for a map of what the world will look like 4oC warmer [18]

Ireland

Winters are expected to become wetter with increases of up to 14% in precipitation under the high emission scenarios by mid-century; summers will become drier with up to 20% reduction in precipitation under the high emission scenarios [19]

The frequency of heavy precipitation events during winter shows notable increases of up to 20% [19]

Declining Arctic sea ice may increase the likelihood of cold continental air outbreaks over Ireland during winter [19]

Sea temperatures may rise by 2 degrees by the end of the century, causing intense, aggressive storms [19]

Levels of ocean acidity in sub-surface and deep offshore waters around Ireland have increased significantly over the period from 1991 to 2010. Increasing atmospheric CO2 is expected to result in increased oceanic acidity [20]

Changes would result in more drought, flooding, heavy rainfall and extreme temperatures that will, in turn, lead to changes in the range and prevalence of pests and diseases, and increased stress for animals [21]

The mean proportion of people living in coastal flood-prone areas is expected to increase, with one of the most notable increases happening in Ireland of 192% [22]